There are many instances in which an inexpensive, portable, disposable heat source is advantageous. For example, such a heat source advantageously could be used to maintain the warmth of packaged food, such as a hamburger sandwich, thereby enhancing the flavor and appearance of the sandwich especially in those instances in which a period of time is required to transport the sandwich from its production site to its consumption site. Such a heat source also can be used to apply heat to a localized area of the surface of a member that is to be heated for one reason or another, such as to accelerate or effect the curing of an adhesive or the like. Such a heat source also may be used as a therapeutic device for the alleviation of pain accompanying sprains, muscular spasms, and the like.